As one of these types of fuel cells, a membrane electrode assembly is disclosed in Patent Document 1. The membrane electrode assembly of Patent Document 1 includes a membrane-membrane reinforcing member assembly, an anode catalyst layer (first catalyst layer), a cathode catalyst layer (second catalyst layer), an anode gas diffusion layer (first gas diffusion layer), and a cathode gas diffusion layer (second gas diffusion layer).
The membrane-membrane reinforcing member assembly includes a polymer electrolyte membrane, one or more flaky first membrane reinforcing member disposed on a main surface of the polymer electrolyte membrane so as to extend along the periphery of the polymer electrolyte membrane as a whole, and one or more flaky second membrane reinforcing member disposed on the first membrane reinforcing member so as to extend along the periphery of the polymer electrolyte membrane as a whole such that the inner periphery of the second membrane reinforcing member does not conform to the inner periphery of the first membrane reinforcing member as viewed in the thickness direction of the polymer electrolyte membrane. Both the first and second membrane reinforcing members are mainly formed of synthetic resin.
The anode catalyst layer is formed to cover the main surface of the polymer electrolyte membrane so as to fill in an opening formed in the first membrane reinforcing member. Likewise, the cathode catalyst layer is formed to cover the main surface of the polymer electrolyte membrane. The anode gas diffusion layer is disposed to cover parts of the main surfaces of the anode catalyst layer and first membrane reinforcing member. The cathode gas diffusion layer is disposed to cover parts of the main surfaces of the cathode catalyst layer and first membrane reinforcing member.
The membrane-membrane reinforcing assembly with the configuration described above is intended to prevent breakage of the polymer electrolyte membrane due to the contact with an end of the gas diffusion layer, and to surely suppress the damage to the polymer electrolyte membrane caused by the end of the first membrane reinforcing member, thereby improving the durability of the assembly.